The objective of this study is to develop human monoclonal antibodies to ganglioside antigens and to determine their potential usefulness in the treatment of cancer. Gangliosides are glycosphingolipids bearing sialic acid and are synthesized at high levels by malignant tissues of neuroectodermal origin (ie., melanoma and neuroblastoma). Gangliosides are usually located on the cell surface. Human melanoma have been shown to express several ganglioside molecules which are uncommon to their normal counterpart. These unique gangliosides include GM2, GD2, O-acetyl gangliosides, N-glycolyl (NeuGc) containing gangliosides, and GD3. Murine monoclonal antibodies to these gangliosides have been developed by other investigators. Over the past grant periods, we developed human monoclonal antibodies to two of these gangliosides, GM2 and GD2, and recently we demonstrated their clinical usefulness through intralesional injection into recurrent cutaneous melanoma. In these clinical studies, we found that ganglioside negative melanoma tissues were not effected by treatment, and that ganglioside expression was widely heterogeneous among melanoma. It thus appears that development of human monoclonal antibodies to other ganglioside antigens is essential for an effective passive immunotherapy for this type of tumor. In this renewal application, we will develop human monoclonal antibody to GD3, and NeuGc containing gangliosides and other melanoma associated gangliosides not yet defined. Epstein-Barr virus transformation, hybridoma and cDNA technology will be utilized to develop both IgM and IgG antibodies. The former two techniques are well established in this laboratory while the construction of human-human IgG chimeric antibodies will be done by collaborative research with a molecular biologist. We will evaluate these newly developed human monoclonal antibodies for their potential therapeutic application in cancer. Tissue distribution of ganglioside antigens defined by the new HuMAbs, binding and cytotoxic ability of the antibodies will be determined.